State-of-the-art digital communication switches, servers, and routers currently use multiple rows of duplex LC connector optical transceivers to meet information bandwidth and physical density needs. To be a commercially fungible product, the optical transceivers must have basic dimensions and mechanical functionality that conform to an industry standard Multi-Source Agreement (MSA) such as set forth in the Small Form Factor (SFF) committee""s INF-8074i xe2x80x9cSFP Transceiverxe2x80x9d document. Many optical transceiver mechanical designs that comply with and add value beyond the basic mechanical functionally set forth in the MSA are possible.
FIG. 1 illustrates a standard configuration for a system 100 including a fiber optic transceiver module 110 and a cage 120. Fiber optic transceiver module 110 contains a transceiver that converts optical data signals received via an optical fiber (not shown) into electrical signals for an electrical switch (not shown) and converts electrical data signals from the switch into optical data signals for transmission. Cage 120 would typically be part of the switch and may be mounted in closely spaced rows above and below a printed circuit board.
When plugging module 110 into a switch, an operator slides module 110 into cage 120 until a post 114 on module 110 engages and lifts a latch tab 122 on cage 120. Module 110 then continues sliding into cage 120 until post 114 is even with a hole 124 in latch tab 122 at which point latch tab 122 springs down to latch module 110 in place with post 114 residing in hole 124. Post 114 is shaped such that an outward force on module 110 does not easily remove module 110 from cage 120.
Module 110 has a delatch mechanism 130, which resides in a channel extending away from post 114. In a latched position, delatch mechanism 130 is outside cage 120, and post 114 is in hole 124. To remove module 110, delatch mechanism 130 is slid toward cage 120 until wedges 132 on delatch mechanism 130 slide under and lift latch tab 122 to a level above post 114. Module 110 can then be slid out and removed from cage 120.
Operation of delatch mechanism 130 can be awkward since removal of module 110 requires pushing in on delatch mechanism 130 while pulling out module 110. Additionally, when module 110 is in an array of modules in an optical switch, modules above module 110 will often block easy access to delatch mechanism 130, making removal of module 110 more difficult. Surrounding modules also make each module more difficult to grip.
Other module delatch mechanisms have been developed in attempts to simplify the removal procedure. One such module has a flexible strip that is attached to the module and resides under the latch tab in the latched position. To delatch the module, an operator pulls up and out on the flexible strip, and the flexible strip lifts the latch tab off the post on the module. Releasing the latch tab and removing the module in this manner requires significant upward force. For many operators, the operation of this delatch mechanism is not intuitive since pulling directly out on the flexible tab will not release the module. Additionally, in a high-density configuration, surrounding modules can make the flexible tab difficult to grip.
Another xe2x80x9cpull-to-detachxe2x80x9d mechanism provides the module with a post on a lever arm and a flexible handle mounted to a rod. When the flexible handle is pulled, the rod forces the lever arm to rotate and lower the post away from the cage, releasing the module from the latch on the cage. The pulling force on the flexible handle then slides the module out of the cage. Return springs that hold the lever arm and the post in position are features molded into the plastic housing. This system requires an operator to apply a great deal of force to remove the module.
In view of the limitations of current systems, fiber optic transceiver modules need new types of delatch mechanisms that are intuitive to operate, do not require excessive force, and are easily accessible in high density module arrangements.
In accordance with an aspect of the invention, a pulling on a delatch mechanism for an optical transceiver module lifts a latch tab off a post on the module before transferring pulling force to the module for removal. Accordingly, operation of the delatch mechanism is intuitive in that pulling directly out on the delatch mechanism pulls out the module.
One embodiment of the delatch mechanism includes one or more wedges that reside inside pockets adjacent the post on the module when the module is latched in a cage. A pulling force on a handle attached to the wedges pulls the wedges out of the pockets causing the wedges to rise and lift a latch tab. When the delatch mechanism moves to a limit of its range of motion, the latch tab is above the post on the module, and the pulling force transfers to the module to pull the module out of the cage. The delatch mechanism can include a spring system that returns the wedges to their respective pockets for latching, allows movement of the wedges relative to the module for lifting of the latch tab, and locks into the module to transfer pulling force to the module during removal. The delatch mechanism can employ a variety of handles including but not limited to a bail, a flexible tab, or a fixed tab, which can be easily accessed even in dense module arrays.
Another embodiment of the invention is a module assembly such as a fiber optic transceiver module assembly that includes a module body and a delatch mechanism. The module body includes a latch post and a pocket adjacent the latch post. The delatch mechanism includes a wedge with a top that is below the top of the latch post when the wedge is in the pocket. When the delatch mechanism is pulled from a first position to a second position, the wedge rises out of the pocket so that the top of the wedge is at or above the top of the latch post.
A spring system can be attached so that pulling the delatch mechanism from the first position to the second position compresses the spring system and transfers pulling force to the module body. One specific spring system uses spring arms having ends in notches on opposite sidewalls of a channel in the module body, and the spring arms and the wedge can be part of an integrated structure that slides along the channel.
Generally, a handle enables a user to pull the delatch mechanism. The handle can include a bail that is connected to an integrated structure including the wedge and/or one or more ridges for gripping when the bail is inconveniently located. Alternatively, the handle can include a flexible tab that is looped though an opening in the integrated structure, or a portion of the integrated structure that extends beyond the module body.
Another embodiment of the invention is a method for removing a fiber optic transceiver module from a cage. The method includes pulling a delatch mechanism from a first position to a second position relative to the module. Pulling the delatch mechanism to the second position moves a wedge causing the wedge to lift a tab on the cage to free a post on the module from a hole in the tab. In the second position, the delatch mechanism is fixed relative to the module so that the further pulling applies force to the module and removes the module from the cage.